As is known, wheel bearings and wheel hubs are highly loaded parts for wheel suspension systems on the chassis of a motor vehicle, which have to withstand a very wide variety of operating loads, in particular in the case of commercial vehicles. A high service life and maintenance free use of the wheel bearings and wheel hubs are decisive competitive advantages for the operators of commercial vehicles of this type.
What are known as insert tapered roller bearing units are used predominantly in wheel bearing units for commercial vehicles.
DE 198 33 436 A1 has disclosed a hub unit complete bearing which has a double row tapered roller bearing with an inner ring, outer rings and, between them, a multiplicity of tapered rollers which are held by a cage. Furthermore, annular seals are provided on both sides of the tapered roller bearing. An inner ring is applied to part of the external circumference of the hub; a second inner ring is formed by part of the outer side of the hub.
Now, if there is damage to the bearing of a wheel bearing unit which is constructed in this way or similarly, presently the entire wheel hub unit is exchanged and scrapped, although the wheel hub itself in fact can still be used.
Even if the mounting of a wheel bearing unit of this type is carried out, for example, in a workshop, said mounting comprises a multiplicity of mounting steps according to the prior art, as are illustrated by way of example and in a simplified manner in FIGS. 1-9, namely:
FIG. 1 cleaning of the wheel hub 2,
FIG. 2 greasing of the inner ring roller crown rings 6, 6′,
FIG. 3 pressing the outer ring 4 of the first tapered roller bearing 1 into the wheel hub 2,
FIG. 4 pressing the outer ring 4′ of the second tapered roller bearing 1′ into the wheel hub 2,
FIG. 5 placing the wheel hub 2 onto the inner ring 5 of the second tapered roller bearing 1′,
FIG. 6 inserting the inner ring 5 and the tapered roller crown ring of the first tapered roller bearing 1 into the wheel hub 2,
FIG. 7 pushing the securing ring 8 into the wheel hub 2 and latching it on the two inner rings 5, 5′,
FIG. 8 inserting the seal 12 of the first tapered roller bearing 1 into the wheel hub 2, and
FIG. 9 mounting the seal 12′ of the second tapered roller bearing 1 into the wheel hub 2.
In said mounting steps, the wheel bearing has to be rotated or turned frequently. Further disadvantages are that the outer rings are not connected fixedly to a dirt protection means or to the seals. Furthermore, two different seals and two different inner rings are often necessary.
The wheel bearing unit is greased during the mounting, with the result that high requirements have to be made of the cleanliness during the mounting process.
Furthermore, DE 198 33 436 A1 relates to a method for manufacturing said hub unit complete bearing which manages with fewer manufacturing steps.
Here, first of all first and second roller cage components are manufactured. Afterward, the first and second roller cage components are inserted into the common outer ring. Subsequently, the hub is pushed into the structural assembly comprising the first and second roller cage components and then the inner ring is mounted onto the hub. This manufacturing method is realized in a relatively complicated manner, since the outer ring and the inner ring have to be mounted separately in addition to the roller cage components.
It would be more economical, in particular for the operator of the commercial vehicle, to retain the wheel hub and to change only the defective wheel bearing or both wheel bearings. However, it is assumed that, in the case of insert wheel bearings with tapered roller bearings, the repair workshops cannot be expected to deal with the complicated and challenging dismantling and mounting of the wheel bearing units. Corresponding knowhow, special tools and absolute cleanliness would be required for mounting the wheel bearing unit, which cannot usually be presupposed in many workshops. An exchange of the complete wheel hub unit is therefore complicated and expensive.